The present invention relates to a processing machine for a silver halide photosensitive material for color photography and a developing method for a color photography using the processing machine.
In processing silver halide photosensitive materials, so-called "mini-labs" for processing the materials within the shops have spread recently, and the time necessitated for finishing the printing of color negative films has been reduced to about 30 minutes to 1 hour. Thus, the service for the clients is now being improved. The important factors for the reduction of time necessitated for the finish are supposed to be improvement of the capacity of the machine, reduction of the processing time, reduction of the make-over rate by improving the printing accuracy and so on.
Since shortening of the processing time contributes very much to the reduction of the time for finish and also to the possibility of reduction in size of the processing machine, the various investigations have been made for developing a technique of reducing the time necessitated for the development, desilverization, washing with water, stabilization and drying steps. It is extremely effective to reduce the time necessitated for the development step among these steps, since the reduction of time without imparing the photographic properties is possible in this step by elevating the processing temperature and increasing the concentration of the developing agent.
In the conventional apparatuses for the mini-labs, the development temperature was usually about 35.degree. to 38.degree. C., and the concentration of the developing agent was about 0.1 mol/l. Polyvinyl chloride, stainless steel or the like is often used for tanks and racks of such processing machine due to the cost and easy processability.
However, it has been found that when a p-phenylenediamine developing agent having a concentration of 0.15 mol/l or above is used in such a processing machine at a temperature of 40.degree. C. or higher, the members of the machine are deformed and therefore the toughness and durability of them are reduced. Such defects are caused probably by an increase of the linear expansion due to the high temperature and the deterioration of the resin due to the developing agent of the high concentration.
Supposedly, the deformation is accelerated by the temperature of 40.degree. C. or above which is higher than the ordinary development temperature and, in particular, the degree of the deformation is increased to an extent higher than the expectation, since when the parts are immersed in the alkaline developer having a pH of at least 10, the substantial coefficient of linear expansion increases. The reduction in the strength and durability is caused because the developing agent is partially oxidized with oxygen in the presence of the developing agent of a high concentration and, thereby, oxygen is reduced to form hydrogen peroxide, which oxidizes and thereby deteriorates the parts. It is thus supposed that the parts are seriously deformed and deteriorated by the synergistic effect of the high temperature and the high concentration of the developing agent.